1. Technical Field
The invention concerns an electric generator, for example a generator in the form of a synchronous generator or also in the form of a ring generator for a wind power installation.
2. Description of the Related Art
Generators are known and are produced for example in large numbers for wind power installations by Enercon GmbH, Aurich, and the power output of such generators is certainly in the region of 500 kW or more, and at its peak also up to 7.5 MW or more.
Such generators are of a diameter which in part is considerable because the Enercon wind power installations do not have any transmission gear and the diameter in that case can fluctuate between 3 and 12 meters (m) or more depending on the respective power output of the generator.
The rotary speed of such generators (also referred to as synchronous or ring generators) is about 10 to 22 revolutions per minute by virtue of the direct coupling of the generator rotor to the aerodynamic rotor of the wind power installation. That therefore involves generators which are classified as ‘slow-running’ and the generators used are in that case multi-pole generators for example with 78 poles or pairs of poles.
As in any electric generator the generator comprises a stator and a rotor (the term rotor in this context is distinguished from the term rotor which is generally used in the case of wind power installations for the rotating part of the aerodynamic system, that is to say the aerodynamic rotor).
The depth of such generators is in the region of 200 to 800 mm.
The generator stator comprises a stator ring which receives laminated sheet assemblies which are provided with grooves and which constitute a closed assembly over 360° at the inside of the stator ring. The turns of the electric generator system are placed in the grooves of the laminated sheet assemblies and the electric power is induced in those turns in operation of the generator.
The sheets of the laminated sheet assembly are conventional dynamo sheets. They are laid manually or by machine in accordance with a given pattern and in that case are also carried by screw bolts which after the laminated sheet assembly is finished are fixedly tightened to press the individual sheets against each other.
The laminated sheet assembly itself after production thereof is finished is fixed to the stator ring, for example by screwing or welding.
As state of the art attention is directed generally to U.S. Pat. No. 3,708,707 A, U.S. Pat. No. 2,973,442 A, U.S. Pat. No. 1,685,054 A, DE 1 232 651 B and DE 2 148 827 A.
The previous system of the generator has proven to be highly reliable.